ignition LEXUS SC300 1991 Service Repair Manual

OKNG
OKNG
YESNO
INSPECTION PROCEDURE
1Check EFI fuse.
C
OK
PRemove EFI fuse from R/B No. 2
Check continuity of EFI fuse.
Continuity
Check for short in all the harness and components
connected to EFI fuse (See attached wiring diagram).
2Check voltage between terminal BATT of engine (& ECT) ECU connector and body ground.
C
OK
PConnect the Check Harness A. (See page TR±34)
Measure voltage between terminal BATT of engine
(& ECT) ECU connector and body ground.
Voltage: 10 ± 14 V
Check and repair harness or connector between engine
(& ECT) ECU and EFI fuse, EFI fuse and battery.
3Are the diagnostic trouble codes still in the memory when the ignition s\
witch is turned OFF?
Check and replace engine (& ECT) ECU.
Proceed to next circuit inspection shown on
matrix chart (See page TR±39).
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±127
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals #10  60 of engine (& ECT) ECU and body ground.
C
OK
P(2) Connect the Check Harness A. (See page TR±34)
(2) Turn ignition switch on.
Measure voltage between terminals #10 ~ 60 of engine
(& ECT) ECU and body ground.
Voltage: 10 ± 14 V
Go to step
.
2Check AM2 and INK fuses.
C
OK
PRemove AM2 and INJ fuses from fuse block.
Check continuity of AM2 of INJ fuses.
Continuity
Check for short in all the harness and components
connected to AM2 and INJ fuses.
Check for open in harness and connector between
engine (& ECT) ECU and battery.
TR±130±
ENGINE TROUBLESHOOTING Circuit Inspection
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Back Up Power Source Circuit
CIRCUIT DESCRIPTION
Battery voltage is supplied to terminal BATT of the ECU even when the ignition switch is off for use by
the diagnostic code memory and air±fuel ratio adaptive control value mem\
ory, etc.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check for short in all the harness and
components connected to EFI fuse.Check EFI fuse.
Check of terminal BATT.
Proceed to next circuit inspection shown on
matrix chart (See page TR±35).
Check operation for the back up.Check and replace ECU.
Check and repair harness or connector
between battery, EFI fuse and ECU.
WIRING DIAGRAM
TR±130±
ENGINE TROUBLESHOOTING Circuit Inspection
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OKNG
OKNG
YESNO
INSPECTION PROCEDURE
1Check EFI fuse.
C
OK
PRemove EFI fuse from R/B No.2.
Check continuity of EFI fuse.
Continuity
Check for short in all the harness and components con-
nected to EFI fuse (See attached wiring diagram).
2Check voltage between terminal BATT of engine & ECT ECU connector and body ground.
C
OK
PConnect the Check Harness A.
(See page TR±30).
Measure voltage between terminal BATT of engine &
ECT ECU connector and body ground.
Voltage: 10 ± 14 V
Check and repair harness or connector between engine
& ECT ECU and EFI fuse, EFI fuse and battery.
3Are the diagnostic codes still in the memory when the ignition switch is\
turned OFF?
Check and replace engine & ECT ECU.
Proceed to next circuit inspection shown on ma-
trix chart (See page TR±35).
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±131
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Injector Circuit
CIRCUIT DESCRIPTION
The injectors are provided to the intake manifold. They inject fuel into th\
e cylinders based on the signals from
the engine & ECT ECU.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Replace ignition relay.
Check voltage between terminals #10 ~ 40 of
engine & ECT ECU and body ground.
Check ignition relay.
Check continuity between terminal E01, E02
and body ground.Repair or replace harness or
connector.
Repair or replace harness or
connector.
Replace injector.
Check for open in harness and connector
between ignition relay and ECU.
Check operation for injectors.
Proceed to next circuit inspection shown on
matrix chart (See page TR±35).
Check and repair harness and connector
between ignition relay and battery.
TR±132±
ENGINE TROUBLESHOOTING Circuit Inspection
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals #20 ~ 40 of engine & ECT ECU and body ground.\
C
OK
P(2) Connect the Check Harness A.(See page TR±30)
(2) Turn ignition switch on.
Measure voltage between terminals #10 ~ 40 of engine
& ECT ECU and body ground.
Voltage: 10 ± 14 V
Go to step 3.
2Check ignition relay.
C
OK
Hint
PRemove ignition relay from R/B No.2.
Check continuity between terminals of ignition relay
shown below.
(2) Apply battery voltage between terminals of ignition relay shown below.
(2) Check continuity between terminals 1 and 2.
Replace ignition relay.
TR±134
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ENGINE TROUBLESHOOTING Circuit Inspection
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OKNG
OKNG
OKNG
3Check for open in harness and connector between terminal E01, E02 of eng\
ine & ECT ECU con-
nector and body ground (See page IN±27).
Repair or replace harness or connector.
4Check for open in harness and connector between ignition relay and injector, injector and en-
gine & ECT ECU (See page IN±27).
Repair or replace harness or connector.
5Check injectors.
C
OK
P
OK
C
Disconnect injector connector (See page FI±50).
Measure resistance of injector.
Resistance: 13.4 ± 14.2
at 20 C (68 F)
Check injection volume of injector (See page FI±52).

Injection volume
55±70 cc/15 sec. (3.4±4.3 cu in.)
Difference between each injector:
Less than 10 cc (0.6 cu in.)

Leakage
Fuel drop: Once drop or less per minute.
Replace injector.
Proceed to next circuit inspection shown on ma-
trix chart (See page TR±35).
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±135
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal STJ of engine & ECT ECU connector and body gro\
und.
C
OK
Hint
PConnect to the Check Harness A.
(See page TR±30)
Disconnect start injector time switch connector.
Disconnect engine & ECT ECU connector.
Measure voltage between terminal STJ of engine &
ECT ECU connector and body ground when ignition
switch is turned to STA.
10 ± 14 V
Go to step 3.
2Check resistance of cold start injector.
C
OK
Hint
PRemove cold start injector (See page FI±27).
Measure resistance between terminals of cold start in-
jector.
Resistance: 2 ± 4
at 20
C (68
F)
Replace cold start injector.
Check and repair harness and connector between
engine & ECT ECU and cold start injector, cold
start injector and battery.
TR±138±
ENGINE TROUBLESHOOTING Circuit Inspection
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NGOK
OKNG
2Check voltage between terminal FPU of engine & ECT ECU connector and body gro\
und.
C
OK
Hint
P(2) Connect the Check Harness A.(See page TR±30)
(2) Turn ignition switch on.
Measure voltage between terminal FPU of engine &
ECT ECU connector and body ground.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page TR±35).
3
Check for open and short in harness and connector between engine & ECT ECU an\
d VSV, VSV
and EFI main relay (See page IN±27).
Repair or replace harness or connector
Check and replace engine & ECT ECU.
TR±144±
ENGINE TROUBLESHOOTING Circuit Inspection
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NGOK
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals TE1, TE2 and E1 of check connector, TDCL.
C
OK
PTurn ignition switch on.
Measure voltage between terminals TE1, TE2 and E1
of check connector, TDCL.
Voltage: 10 ± 14 V
Check and replace engine & ECT ECT.
2Check continuity between terminal E1 of check connector, TDCL and body ground.
Repair or replace harness or connector.
3
Check for open and short in harness and connector between engine & ECT ECU and che\
ck con-
nector, TDCL (See page IN±27).
Repair or replace harness or connector.
Check and replace engine & ECT ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±147
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